Manchester United midfielder Marouane Fellaini will wait until the January transfer window before deciding whether to leave Old Trafford despite the arrival of Nemanja Matic from Chelsea. The Serbia international has joined from the Premier League champions on a three-year deal for an initial £40m, a signing which manager Jose Mourinho has described as a "Jose Mourinho player".

It was understood that confirmation of the signing of Matic would trigger Fellaini's move to Galatasaray, with the Guardian claiming he would sign a four-year deal worth €4m [£3.6m] a season. Sporting director Cenk Ergun confirmed the club were in talks with the Belgium international, who has less than a year to run on his current contract and a deal was expected to be concluded this week.

Mourinho quickly moved to shut down any talk of Fellaini leaving United, suggesting it would be easier to sign him than the 29-year-old; appearing to end speculation regarding his departure from England. Both Mourinho and Fellaini are understood to be close, with the latter claiming last season he would break his foot for the Portuguese coach, such was his commitment to the cause.

Fellaini played 47 times for United last season as the club won the English Football League Cup and the Europa League, which earned them direct passage into this season's Champions League. Despite being regularly involved throughout the campaign there remains uncertainty over his future with the ex-Everton and Standard Liege man having entered the final 12 months of his contract.

Matic is expected to be first choice in the United midfield when the new Premier League campaign starts in less than a fortnight, a decision which is likely to impact on Fellaini's opportunities. However, it is understood that Fellaini will risk waiting until the middle of the term before deciding whether to leave, giving Mourinho six months to convince the 6 ft 3ins midfielder that he remains in his plans.

Central to Fellaini's decision is the upcoming 2018 World Cup in Russia. Fellaini was included in Roberto Martinez's most recent Belgium squad for June's friendly against Czech Republic and World Cup qualifier in Estonia but a domestic campaign on the periphery could hurt his chances of being selected next summer. Roma's Radja Nainggolan, Leander Dendoncker of Anderlecht and Tianjin Quanijian's Axel Witsel represent his main competition for a place.

Fellaini played 47 times for United last season as he helped them qualify for the Champions League.Getty Images